The present invention relates to a conductive surface layer, for example to form an electrode.
Piezoelectric elements, for example oscillator crystals, are generally provided with two film or sheet-like, oppositely disposed electrodes that are essentially parallel to one another; up to now these electrodes have, for example, been made of such precious metals as gold, chromium, silver, or also from tungsten or the combination of various other metals. Furthermore, the electrodes can each also be formed from the aforementioned metallic materials in the form of individual superimposed layers. During the course of forming the film or sheet-like electrodes, in other words during the manufacture, for example by vapor deposition, it can happen that the thereby occurring thermal stress is so great that the respective curie temperature of the piezoelectric element is partially reached or exceeded, as a result of which a depolarization of the piezoelectric component can occur. Unfortunately, when the curie temperature is reached and exceeded, the piezoelectric component looses its specific piezoelectric properties, at least in part. The general rule is that the half curie temperature should not be exceeded.
A further drawback or problem encountered during the manufacture of piezoelectric components was that the generally metallic electrodes often exhibited an inadequate adhesive and wear strength over the entire surface or over portions thereof, and also exhibited an electrical conductivity of the electrode surfaces that varied over the course of time that up to now also varied over the entire electrode surface or portions thereof and varied with time. A further drawback of the heretofore known electrode formation on piezoelectric components consists in the relatively great mechanical damping of the oscillation characteristics of the component due to the thick metallizing (up to 2.times.10.sup.-2 mm for silver) and the inertia of the metal electrodes connected therewith.
A further drawback that occurs when stacking several piezoelectric components is the gap deflection that occurs with thick metal electrodes.
It is therefore an object of the present invention to provide a conductive surface layer that avoids the aforementioned drawbacks, that is more economical to produce than was the case with heretofore known layers, so that, for example an improvement of the oscillation characteristics of an oscillator crystal are achieved and better resonant or oscillator circuit qualities can be achieved, and with which the aging rate is reduced in comparison to the heretofore known components.